Protection against reversal of energy.



' No; 811,265 PATENTED JAN. 30, 1906,

v 0% Leonard W Hsorr1,

L. WILSON.

PROTECTION AGAINST RBVERSAL OF ENERGY.

APPLICATION FILED MAY 2, 1904.

2 SHEBTS-SHBET 1,

vIIIIIr Witnessgs: Inventor:

No. 811,265 PATENTED JAN. 30, 1906. L. WILSON.

PROTECTION AGAINST REVERSAL OF ENERGY. APPLICATION FILED MAY 2, 1904.

Z SHBETSSHBET 2.

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LEONARD: winson or rir rsrinnit),- MASSACHUSETTS; ASSIGNOR To versal ofenergy'; and its object is toprovide more reliable and positive'means' for such- Toal lwhom-it Mayhbncern: p 'Be itknown that I, LEONARD WILSON, a 1 subject of the King of Great Britain, residing at Pittsfield', inthe county of Berkshire and STANLEY ELECTRIC INIA'NUFACTUR'ING COMPANY; OF- PITTSFIELD,

Massaciiusnrrs, A'CQRPQRXIION'OF N WJERsEr;

"eledi gejiioniieamsi BEVIERSAYL' or ENERGY. I

Specification of Letters h s.

Patented Jan. 30, 1906.

Application filed May 2,1904 Serial No. 205,850.

Stateof; Massachusetts, have invented certain new and useful Im rovements in Protection Against Reversal of Energy, of which the following is'a specification.

. invention relates to the protection of alternating-- current apparatus against rerot'ection than have hithertobeen devised. n' the case. of'such alternating-current apparatus-as, for instance, a generator connected to common bus-bars with other genera torsa reversal of the flow of energy may occur upon the failure of the apparatus and may result in' its damage or destruction, and it is advisable to provide means for opening the'circuit of such apparatus when such reversal occurs. To accomplish this end, it

has been proposed to employ'a reverse current cut-out'operating-on the principle of a ofthe two windings being such that when shunt-motor or wattmeter, the connections the current is in its normal phase relativeto the potential a turning movement of the cut-' out will be produced in a, given direction,

while upon a reversal of the current phase,

relative to the potential a turning movement in the opposite direction, and a consequent operation of the cut-out will be produced.

Such 'an'arran ement is shown and described in the Unite States Letters Patent No.

638,084, issued to Leonard Andrews,'. No vember 28,1899. Although such a cut-out "affords adequate protection against a normal flow of reverse current,it is likely to fail upon 4o to be protected.

a reverse current "of large amount as, for instance, upona short-circuit of the apparatus In such a case the potential across the terminals of the apparatus may fall' to a very low value, insriflicientto-furnish the potential'coil of the cut-out with the v j proper. amount of current for operation, and

evenif a certain amount'of potential still exists at the terininalsof the apparatus a heavy emenaflow may so overpower theeffectoff thefpetentialcoil asto render the dev ce m-' operative;

By my me tion I provide means for i the protection of alternating-current apparatus against reversal (if. energy,- which shall he at all times reliable in its action regardless of the drop of potential or amount of reverse- .c'urrent flow.

My invention will best be understood by referenceto the accompanying drawings, in WhlCl1-- Figure'l shows an arrangement embodying my invention applied to an alternatingcurrent generator. Fig. 2 is an explanatory diagram showing the means for adjusting the o eration of the cut-out device, and Fig. 3

s ows a series of curves illustrating the operation of the device. a 1

Referring to Fig. 1, A represents the stationary armature of analternating-current generator carrying the armature-coils a. F represents the revolving field structure, carrying the field-polesf and mounted on the shaft S. s' srepresent collector-rings on shaft S, b

means ofwhich current is led to the fiel Winding from the exciter E or other "source of current. The armature-terminals a of the generator are connected to the mains or bus-bars X. It is evident that if other sources of current are connected to the busbars X and if the generator A'drops out of synchronism, or if its field-circuit becomes open from any cause, a reversal of energy will take place and current will flow from the busbars X to the generator, which, if allowed to continue, may result in the damage or destruction of the generator.- Furthermore, as

' and by properly coinmutating it introduce it into one Winding of a direct-current relay. Thus C represents a commutator or rectifier mounted on shaft S, two brushes of which, b b, are connected to the secondary of a series transformer T, the primary of which is connected inone of-the generator-leads. A secondset of brushes '1) is connected to the on the movable element d of the olarized-relayD, theother'element of W-lllCh' has its winding d energized from a source'of constant current, such as battery B, or, if preferred, this element may be formed of a permanent magnet and the lieldwinding d omitted. The movable member (1 of therelay carries an arm. H, winch when the movable member (1 tends to turn in a counterclockwise direction is restrained by the stop 7t, but which when the armature a turn in a clockwise direction bridges tacts h, closing a circuit from the battery through a tripping-coil of a swit. i G, arranged to open the circuit of the generator.

Referring now to Figs. 2 and 3, the action of the commutator will be explained. In Fig.2, (1 represents diagrammatically the armature-winding, and f f the field-poles. C represents the cormnutator, which is carried by the shaft and rotates ith the field-poles The two sets of brushes 1) and Z2 Z1 are shown connected to the secondary of trans former T and to the armature oi relay D, respectively. With the brushes arranged as shown, it is evident that the direction of current through the armature of relay D ill be reversed relative to that in transformer T whenever the brushes 1) Z) pass from one sec tion of the commutator to the other. Moreover, with the brushes fixed in any given position it is evident that the time of this never sal is fixed relative to the position of the iield structure, since the commutator revolves with the field structure. Consequently this reversal is fixed relative to the potential induced in the armature-winding it, since this potential depends upon theposition of the If the brushes 1'': here so placed that they pass from one section of the commutator to the other at the instant that the field-poles are in the position of zero induced electromotive force in the armaturewinding A, and if the current in the secondary of transformer T is in phase with or in opposition. to the induced electroi'notive force in winding (1 the current curve in the armature of relay D may be represented by the curve i in diagram 1 of'Fig. 3, the. induced electromotive force in armature abeing represented by the curve e in the same figure. That is, the'current through the armature of relay D is a pulsating unidirectional current and coact'ing with the constant field of the relay will produce a torque in a given direction. vNow assuming that the brushes remain lined in the same position, if the current in the secondary of transformer T is ninety degrees out of phase with the induced electromotive field-poles f.

force. in the armature a the current curve of the armature of relay D will be represented by the curve i in diagram 2. The point of commutation of the current is shifted ninety degrees relatively to the current curve from that in diagram 1 and no troque can be produced in relay D. The same diagram 2* 6 5 .would also represent the current cur-n1 it the current in the secondary ol' tra reformer T were of the same phase as in Fig. 1, but the brushes shifted ninety degrees, or, in other words, the change of the current curve in diagram 2 may represent either a shill ng ol the curre. t phase or a shiltin of the brusluu. Consequently it will be seen 1.! t by p operly adjusting the brushes the cm: :i curve of diagram. l may be ()l'JltllllPll any PlLLlSi rotation oi the .'".':nt in tlw sicon-llary transformer 'l. to the induced lcctrmiiw tive force in armature-winding rt. l\ w L some that the brushes 1) t are properly ola relative to the field-polesf, so that diagrt I 1- represents the current curve in the armature of relay D when the current. in the pri mary of transformer T, or, in other worm, the current in the winding a is in phat vith the induced electromotive for" this WCH .i be the condition of unity power 3: ctor. Yl'ir i the brushes maintained fixed in position diagram 2 would represent the conditions for zero power factor, and diagram 3 would represent the conditions for a eomplcte reversal of current-that is, when the one hundred and eighty degrees out of phase with the induced electroniotive 01 12 in comparing diagrams 1 and 3 it will be seen that the current curves in both represent a pulsating unidirectional current; but the di rection of current is reversed. Consequently a reversal of current in armature-winding (1. relative to the potential produces a reversal of the direction of the torque of the armature ofrelay D and a consequent opening of the generator-circuit by means of the arrangement shown in Fig. i. It will be seen that the operation of the relay is in no way dependent upon the potential across the terminals of the generator, and cmisequcntly its operation is in no way affected by a drop in this potential.

As has been said heretofore, a reverse-current relay of the wattmetcr type is subject to the objection not only of failure of current in the potential winding upon a short circuit, but also to a possible overpowering of the potential flux upon the llow of a heavy shortcircuit current. A protective device arranged in accordance with my invention is not liable to the first objection, and in order to avoid the second I design the series transformer T, so that it will become saturated at a small fraction of normal full-load current. The

amount of current-flow of the secondary of transformer T is consequently limited and can. never reach an amount liable to produce a false operation of the relay on an overload or a failure to operate upon a reverse shortcircuit c'urrcnt. The employment of a saturated transformer has the further advantage that a practically uniform torque of the de vice D is obtz .ined over a wide range, thereby enabling the relay to operate upon a com paratively small reverse current, while at the current is i iii) t sametime reliable upon "a heavy shortbircuitcurrentL'Ihe use of a Saturatedseriestransformer" produces a shifting'of the relative phases ofthe currents in its primary and secondaiy', the currentsbeing no longer nea'rly one hundredjan'd eightydcgrees apart, as in an 'u'n'sat'urated transformer, but little more thanninety degrees apart This, how

I ever, is" of no importance, since this shifting of phase may bec wholly compensated for sim- .ply'byshifting the brushes.

', vIn adjusting'fthe brushes'it is well to bear in l mind that the usual reverse current is not of unity power factor, but is ordinarily about one hundred and fifty degrees out of phase with the electromotive force. This characs teristic also may be provided for by operly placing the brushes.

, "Although I'have shown my invention'ap plied toan alternating-current generator, itis' in no way limited to this particular application. It may also be utilized with receiving apparatus, such as synchronous motors or r Qtary converters, to prevent their returning energy to the line upon a failure of the line voltage. My invention is applicable to any alternating-current apparatus which is-liable ..,'to a reversal of energy when means can 'be provided for driving a commutator synchronou'sly and in phasewith'the electromotive force.

Since the function of the commutator is I merely toreduce the alternating current from the secondary of the transformer and the direct current from the battery B tothe same kind of. current, it isobvious that either of i I the two currents may be 'commutated. The "arrangement shown,- however, is the preferred form.

Although I have shown a device D as a re lay arranged to close the circuit of the tripping-coil of a switch, my invention is not lim- .ited to this particular arrangement The de, -viceD may be directly connected to operate the switch, as in the arrangement shown in 'United States Letters Patent No. 638,084,

heretofore cited. Accordingly I do not de-' f sire 'to limit myself to the particular construction and arrangement here shown, since changes which do not depart from the spirit of my invention will be obvious to those skilled in the art.

, 1 What I claim asnew, and desire to secure by Letters Patent of the United States, is-

1. In combination, a main alternating-current circuit, a local circuit in which the cur rent varies in phase with variation of phase of the current in the main circuit, a commutator in said local circuit rotating synchronously with the cycles of the electromotive force of the main circuit, a device having relatively movable members and energized both by the commutated current in said local circuit and by a constant flux, and a switch in the main circuit controlled by said device.

2. In combination, a main alternating-cuirent circuit, atloral circuit in which the cur-.

' rent varies in phase with variation of phase of the current in the main circuit, a commutator in said local circuit rotating synchronously with 'the'cycles of theelectro'motive force of the main circuit, a device having relatively movable members, one of said members'bein energized by the commutated current in said local circuit and the other member being energized by a constant fiux, and aswitch the main circuit controlled by said device.

3. Incombination, an alternating-current dynamo-electric machine, a local circuitin which the current varies in phase with variation of phase of the'current in said machine, a commutator in said local circuit rotating with the rotating member of said machine, a device having relatively moyable members and energized. both by the commutatedcurrent in said local circuit and by a constant flux, and

a switch in the circuit of said machinecontrolled by said device.

4:. In combination analterhating-current dynamo-electric machine, a local circuit in which the current varies in phase with variation of phase of the current in'said machine, a commutator in said local circuit rotating'with the rotating member of said machine, a de vice having relatively movable members, one of said members being energized by the commutated current in said local circuit and the a other being energized by a constant fiujr, and

a switch in the circuit of said machine con trolled by said device.-

5. In combination, a main alternating-current circuit, a local circuit in which the cur:

rent varies-in phase with variation of phase of the current in the main circuit, a source of rect current, a device energized both by ourrent from said local circuit and current from said source, a commutator adapted and arranged to commutate one or said currents and rotating synchronously and in phase with the electromotive force;v of the main circuit, and a switch in the main circuit controlled by said device.

6. In combination, an altenating-current dynamoelectric machine, a local circuit in which the current varies in'phase with variationof phase of the current in said ma ChlIlQgfii source of direct current, a device energized both by current from saic l local circult and by current from said source, a mum relative to the electromotive force, and a BIO switch in said main circuit controlled by said device.

8. In combination, a main alternating-current circuit, a device energized by a constant flux, means for producing in said device a second flux reversible in direction when the current in the main circuit reverses in phase relative to the electromotive force and independent in strength of variation in current strength in the main circuit-over wide ran es, and a switch in the main circuit contro led by said device.

9. In combination, a main alternating-current circuit, a local circuit in which the cur rent varies in phase with variation of phase of the current in the main circuit and is indesaid loca pendent in strength of variation in the main current strength over wide ranges, a source of direct current, a device energized both by current from said local circuit and current from said source, a commutator adapted and arranged to commu-tate one of said currents and rotating synchronously with the cycles of the electromo'tive force of the main circuit, and a switch in the main circuit controlled by said device.

10. In combination, a main alternatingcurrent circuit, a local circuit in which the current varies in phase with variation of phase of the current in the main-circuit and is independent in strength of the strength of the main current over wide ranges, a commutator in said localcircuit rotating synchronously with the cycles of the electromotive force of the main'circuit', a device having relatively movable members, one of said members being ener ized by the commutated current in circuit and the other member being energized by a constant flux, and a switch in the main circuit controlled by'said device.

1 1. In combination, an alternating-current circuit, a series transformer havin its primary included in said circuit and a apted to be saturated by a fraction of the normal current in said circuit, a source of direct current, a device energized both by current from the secondary of said transformer and by current from said source, a commutator adaptedand arranged to commutate one of said currents and rotating synch "onously with variation of phase of the electromotive force in said circult, and a switch in said circuit controlled by said device.

1 2. In-combination, an alternating-current dynamoelectric machine, a series transformer having its primary in series with said machine and adapte to be saturated by a fraction of the full-load current of said machine,

a commutator connected to the secondary of said transformer and rotating with the rotating member of said machine, a device having relatively movable members, one of sai members having a winding connected to said commutator and the other member being en ergized by a constant flux, and switch. in. the circuit of said machine controlled by said. device.

13. A device for protection against reversal of ener in an alternating-current circuit, comprising a member energized by a constant flux and a second member movarlerela tively to the first member and ener ized by a oommutated current varying in with variation of phase of the cu rent in said circuit, and a switch in said circuit controlled by said device.

14. A device forprotection against reversal of energy in an alternating-current circuit comprising two windings, one energized ,from a direct-current source and the other from' an altenating-current sour-1e in which the current varies in phase with variation of phase of the current in said circuit, means for commutating one of said currents, and a switch in said circuit controlled by said device.

15. Areverse-current cut-out for alternatingcurrent circuits comprisin a rectifier, and a polarized relay actuated y the rectified current.

16. Areverse-current cut-out for alternating-current circuits comprising a rectifier driven synchronously with the cycles of the electromotive force in said circuit and a polarized relay actuated by the rectified current.

17. In combination, an alternating-current circuit, a rectifier in said circuit, a polarized relay supplied with current from said rectifier, and a circuit-breaker controlled by said relay.

18. In combination with an alternatingcurrent circuit, a series transformer having its primary included in said circuit and having a core adantedto be saturated by a fraction of the full-load current in said circuit, a

rectifier in circuit with the secondary of said. transformer, a polarized relay supplied with current from said rectifier, and circuitbreaker controlled by said relay.

In Witness whereof I have hereunto set my hand this 29th day of April, 1904.

LEONARD WILSON.

- Witnesses:

J. R. ANDERSON, H. M. AoLY 

